The invention relates to a mounting for a coiled ribbon spring and is particularly, though not exclusively, applicable to sash springs used in sash frame tensioning arrangements for windows.
Such coiled ribbon springs are in the form of a flat coil with an open area at their center and two free ends, an outer one on the outside of the coil and one on the inside; the springs being similar in construction to clock springs except that the inner free end is not (as in a clock spring) secured to a fixed point.
It is known in the art to mount such coiled ribbon springs on a drum within a hollow channel in a window frame by means of a screw or other fixing, about which the spring is able to uncoil as an outer free end of the spring attached to a window sash moves away from the coil as the sash is moved. The drum may be arranged to be stationary or to rotate with the spring, through the drum is provided only to guide the spring and is not operatively secured thereto (thus, if the spring were unwound too far, it would be unwound completely from the drum).
It is a feature of these known mountings that the spring is supported from the open space within the coil so that an upper part of the coil rests on the drum with a lower part of the coil slung below the drum and not supported thereby. It is, as stated above, a feature of such springs that the inner free end of the spring is not secured to any point (on the drum or elsewhere) such springs being referred to in some instances as "constant tension" springs.
The drum is merely to provide a reaction member and as a means of retaining the body of the spring loosely in position in the channel as its free outer end is uncoiled.
It has been a disadvantage of this known type of mounting that the spring is not silent in use, possibly due to relative movement between the inner, free end of the spring and the spring support drum.
The present invention seeks to overcome this disadvantage.